Every seat in given vehicle can be customised to serve special function. Specified in Vehicles.xml:

0Seat00000000

Examples of seats specified for Ice Cream Truck:Driver - merc sitting here is a driver, it has to be taken or vehicle won't move.Riding Shotgun - sits next to driver, only passenger with good view on the right side of the van.Serving Hatch #1 & Serving Hatch #2 - their view is limited to the left side of the van (since serving window is on the left).Cargo #1 & Cargo #2 - mercs don't see anything and can't shoot, but are also invisible from outside.Cargo #3-#6 - same as above, but will only be used if you manually increase SeatingCapacities (some people change it to fit entire squad in vehicle.)

I also specified seats for Hummer, Eldorado and Jeep (decreased seating capacity of Jeep to 4, it's like 1/2 size of Hummer...)

Selecting, Changing and Swapping Seats

You can select specific seat that you want your merc to take by clicking on vehicle ctrl+RMB (as opposed to normal ctrl+LMB to get in).
You can check what seat your merc sits on by hovering over his portrait - seat's name is displayed above traits. Each seat is also linked to position on team panel.
You can also change seat while in vehicle (ctrl+RMB on vehicle again) or using ctrl+left/right arrow (20 APs in combat, less than to exit and enter again). Swapping is also possible, but APs are deducted from both mercs.

Don't worry if you don't care much for micromanagement. You can still use ctrl+LMB as before, and merc will take first empty seat by himself. Possibility > neccessity.

Compartments

You cannot switch between seats that aren't in the same compartment (OK, you can, but not in combat). For example, you can hide your merc in trunk of Eldorado, but if you want him to shoot, he'll need to get out first - he won't magically teleport to the back seat - and then he'll need APs to get back in vehicle if you plan quick getaway. It of course greatly decreases effectiveness of using trunks in hit & run scenarios.

Noise

Vehicles now make a proper amount of noise - 15 on slow drive, 25 on fast drive.

Physical Structures

Fixed and created new JSD structure files - now vehicles have proper, different (eldorado != truck) shapes, and are no longer fully transparent. Position of merc in vehicle is important and influences his range of view (as per seat). For example ice cream van has window on only one side and if you want to maximize its effectiveness in drive-bys you have to A) have enemies on correct side of it B) place mercs on correct side of vehicle. Just like in video posted by Taro (no shooters on the roof though). You can also hide behind parked car.Ice Cream Van, now and before, courtesy of JSDEditor_v1.2.1. Note that "before" version was shared by all cars. Note it also looked like roadkilled frog.

Operation "Trojan Popsicle"
New features in practice (warning, massive amount of pics):

1. D13: Drassen Mine, south outskirts of town. Hamous is still unknown to enemy forces. He holsters his gun and gets behind the wheel. Two other mercs get in the van too, but hide in the back, in the cargo compartment.No point in getting cold feet now.

2. Hamous drives around town, discovering enemy positions.It's time to stroll through the valley of death... IN ICE CREAM VAN.

5. Enemies gather around and bullets fly by. Few odd shots graze car body (nice job, Bud, clearly you just wanted to make our disguise more plausible).Enemies about to get what they deserve (and it ain't gonna be ice cream).

6. Just as enemies gather on the left side of the van, armed mercs inside take positions behind a window.Last freeze-frame of the magnificent seven in their final moments.

7. Passengers open fire and add a grenade for a good measure.Murder in cold blood.

8. After they are spent, Hamous hits pedal to the metal and gets the hell out before enemies get a chance for any serious retaliation.Sorry, we need to restock on vanilla. Gonna be back soon!

- externalised vehicle seats influence position of passenger, field of view, ability to shoot and being hidden,
- seat can chosen by using ctrl+RMB on vehicle,
- seats can be changed or swapped while inside vehicle,
- remade JSD files for cars,
- vehicles aren't transparent anymore,
- vehicles are louder than people, depending how fast they move.

Screwing around, I reenabled AI tanks movement for a test. Animation looked silly as predicted, and I'd also need to look into AI, as at the moment their actions were a bit silly too. Out of four two decided to not move anyway, and two others used "drive right into merc's face and shoot him with machinegun at point blank" tactic - while it was surprisingly efficient against the player, it wasn't very realistic. But some dabble, and moving (massive) tanks are probably almost certainly a possibility. Jeeps should be more easier.
By the way, shouldn't food stored in Ice Cream Truck be safe from spoiling?

I don't know if it is a bug or intended, but I can't leave the sector in tactical when the vehicle is placed on the edge of the map and I want to go to the next sector. It shows the disabled "move icon" and when I click it tells me "[MERC NAME] is too far away."

EDIT: Of course leaving the sector inside the vehicle in tactical should only be possible, if the vehicle is allowed to drive in the adjacency sector. For example, the ice cream truck is only allowed to drive on sectors that have roads defined in strategy, so it should be the same sectors in tactical.

Every now and then I get an urge to play JA2, and I come to the forums to check out what happened since, and every time everything's different... but not normally THIS different! Pretty awesome timing. You modders are the kings of re-playability. Thanks a bunch!

Slightly off topic but it's been a long time since a stable release, when's the next one due? And if we get all the bugs out of this feature (I'll help if I run into any), do you think it might become part of that?

@Xavager: You updated your gamedir, but didn't update your .exe. To make use of externalised seats and new JSDs in gamedir 2038 you'll need .exe built on at least 7212 revision of source (though fresher is better, as always).

To elaborate: original JSDs for vehicle were transparent, and vehicles were visible for player and enemies as long as anyone of their team had middle grid of vehicle in sight. JSDs in 2038 aren't transparent anymore (which is why you don't see vehicles on 7205), and I changed visibility check in source to make vehicle visible if any part of vehicle is visible (since middle grid is now obscured by the rest of vehicle structure). It also means enemies will notice your vehicle and possibly attack it even if just part of it is sticking out of cover - previously you could hide behind tree or something and as long as a very middle of vehicle is obscured, you're invisible to enemies. I think something like that was also possible in Half-Life 2 where you could hide by holding a brick in front of your face I left tanks out of it since I didn't change their structure and it would make life easier for player if he was able to notice tank by seeing any part of it (but after they can move in tactical I'll probably add this as an option too, they're already hilariously overpowered).

TO vehicles are even in similar graphic style. Except tank, but vanilla tank just needs those extra directions.

And Fallout never fails. I remember how disappointed I was when discovered Highwayman in 2 can only drive on map. In Tactics my character was driving around while shooting one-handed with giant revolver... but Tactics wasn't the same, and its vehicles lacked style :< But those fan made certainly don't!

Note it's off by default, due to:
1) immersion breaking silly animation (at least at the moment). OK, it's not really that bad. If you see tank it usually sees you, and if it sees you it's too busy killing you, so moving happens mostly out of your sight anyway.
2) let's face it, you're pretty much dead with it on. Normal tactics: stepping out of cover, firing LAW, hiding before turn ends? They tried it, didn't work out so well (OK, I cheated here by using version of map with fortifications around tanks removed and orders set to seeking):Wait! Violence is not an answer! Let's talk this through!

Tank AI isn't perfect, but it's not much more imbecilic than other enemies. To fully utilise the feature you'd need mappers to set orders for tanks other than stationary, specify patrol points and put them in the open - on vanilla maps they're frequently blocked with fortifications - cause, you know, they couldn't move before.

Normally enemies don't use launchers unless there's high enough chance that its missile will reach the target without hitting anything on the way. It makes sense, since most soldier have very limited ammo, and wouldn't want to waste their only shot. But tanks have unlimited ammo... There's something between me and the target? Well, boo-hoo, I'm a tank! Let's blow this shit up!

By default enemies won't throw grenades and use launchers until they know they can hit at least two opponents at once - or are wounded bad enough. It's partly to ensure they won't waste it and partly an artefact from JA1/DG (OK, maybe that's just me, but if I had a grenade I wouldn't save it UNTIL I GET SHOT).
Point is, once again, tanks have unlimited ammo (or even playing by real world rules, enough to blow up every merc twice). It also prevents such absurd tactics like soloing tanks in order to avoid cannon fire.

If TRUE, you will notice enemy tank as soon as you see any part of its structure, not only the middle grid. That actually makes fighting tanks slightly easier.

Army Uses Tanks in Patrols

If there's one thing intro taught us, it's that Deidranna has no qualms over sending bunch of tanks all the way up to Omerta to slaughter civilians - but in normal gameplay only tanks you meet sit camping around Meduna. At the game start there are 30 enemy groups patrolling Arulco, consisting mostly of army soldiers. If Strategic Gameplay Settings > ARMY_USES_TANKS_IN_PATROLS is set to TRUE, some of them will be randomly reinforced with tank. Amount of tankified patrols depends on difficulty level - from ~10% on Novice to ~40% on INSANE. Now you have real reason to avoid patrols...

Army Uses Tanks in Attacks

Drassen Counterattack is clearly underpowered (said no one ever), so with Strategic Gameplay Settings > ARMY_USES_TANKS_IN_ATTACKS set to TRUE, one soldier per attacking group will be randomly replaced with tank. Chance depends on difficulty level. Same applies to other cities taken and scripted offensives if you play with AGGRESSIVE_STRATEGIC_AI.

Both above options are off by default - because with it on you're so dead that it's not even funny. 80 soldiers during Drassen counter-attack? That's cute. How about 76 soldiers and 4 tanks?

You can use both Army Uses Tanks options even with ENEMY_TANKS_CAN_MOVE_IN_TACTICAL off, but that means attacking tanks will spawn at the edge of sector and won't move - which would be counterproductive.

Resting Guns In Vehicles

Done. I considered another tag for externalised seats, but I can't think of any place in vehicle you could shoot from without resting gun on something.

Resting Guns On Vehicles

It's more of a fix really, but now you can rest your gun on dashboard of any vehicle - they won't mind. Now we just need squad cars and spikes strips, and Higginses can feel at home again (Turtle prefers donut shops).

Creepiest moment during testing tanks:
After entire squad except Ivan got obliterated (together with entire building) in a single turn, and Ivan himself got hit in the face by a 90mm shell and was lying knocked out but conscious on the ground (somehow he was ALWAYS the last one to die), one of tanks exclaimed "I want candy." - which was instantly followed by "Do you want to surrender?" prompt. My brain exploded.

- feature: tanks can move around in tactical. Set with Tactical Gameplay Settings > ENEMY_TANKS_CAN_MOVE.
- feature: tanks can ignore chance to get through and destroy enemy cover even if it probably won't hit anyone behind it. Set with Tactical Gameplay Settings > ENEMY_TANKS_BLOW_OBSTACLES_UP.
- feature: tanks can use cannon even against single mercs and in perfect health. Set with Tactical Gameplay Settings > ENEMY_TANKS_DONT_SPARE_SHELLS.
- feature: tanks can noticed as soon as any part of it is visible. Set with Tactical Gameplay Settings > ENEMY_TANKS_ANY_PART_VISIBLE.
- feature: depending on game difficulty enemy patrols at game start can be randomly reinforced with tank. Set with Strategic Gameplay Settings > ARMY_USES_TANKS_IN_PATROLS.
- feature: depending on game difficulty enemy groups created during offensives can include tanks. Set with trategic Gameplay Settings > ARMY_USES_TANKS_IN_ATTACKS.
- feature: mercs in vehicles automatically rest their guns,
- fix: guns can be rested on vehicles,
- rewritten code to allow putting enemies inside vehicles,
- added missing descriptions for all vehicle options to INIEditorJA2Options.xml.

Will the tank become angry and loose morale if someone is resting his gun on him while shooting? =)

EDIT: using rocket launchers and grenades to pass through obstacles, sandbags and concertina makes sense to regular soldiers, too.
EDIT2: Is it possible for Ivan to capture tank? =)
EDIT3: M60 Patton as PNGs
EDIT4: finally, some use for HEAP rocket rifles

EDIT: using rocket launchers and grenades to pass through obstacles, sandbags and concertina1 makes sense to regular soldiers, too.

True, they should be a lot more liberal with explosives, especially to counter the player's ability to build strongpoints of his choice now rather than use 'mapper tweaked' ones that might not be optimal.

Have you been able to solve the turret-problem? As in, can a tank move with its turret not looking into the direction it is moving in?

Not sure wether you've already done that, but having the tanks destroy scenery by moving over it is probably not difficult to accomplish, apart from finding the correct code location. Could even be used to flatten people

@Sevenfm:
EDIT2: Not unless we start putting enemy soldiers in tanks as a crew, then figure out a way to kill the crew without destroying tank, be it by piercing armor in selected tank structure segments or by incorporating climbing on tanks, opening hatch and throwing grenades down, which would require climbing on any mobile structure other than roofs. That being said climbing on vehicles would be pretty cool.Hamous and his cone of vision.

And maybe not that hard to make. Now just to make merc on roof move together with vehicle and fall down when driving too fast. And stop mercs from climbing on each other O_o

@Flugente:
No :< I rigged changing bodytype (TANK_NW TANK_NE) depending on movement direction, and it kinda worked, but I need at least two more, (optimally 6) animation sets for extra bodytypes. I can just cut turret from all frames in original NW, paste it on rotated tank base and make full animation sequence from that.
More elegant solution would be to use just tank base for bodytype, and display turret's on it independently like in Sevenfm's EDIT3 Patton, but haven't even look into coding that yet. Blocking visual rotation (changing current frame in sti) when moving to keep turret looking at sides should be very easy however.

Road kills are next on to do list, I guess for tanks it can double as scenery kill.

btw i loved ENEMIES_BLOW_OBSTACLES_UP. If I understand correctly then i can't hide in the toilets during DCA.

Those tags already exist
I don't think this will work in the situation you mentioned - in that case, the AI does not technically know where the player is inside unless one of it's soldiers see the player (at that point it could use spotting though). It would also need to plan how to destroy the walls (destroying a wall with just grenades can be done by dropping some near it and then igniting it with another one, but teach that to the AI...).

just a thought: Wouldn't it be nice, if the AI could use Tanks in the counter attacks of cities like Alma, Grumm, Cambria, Balime? Depending on progress or something ... it would fit the game's intro movie so well

When controlling vehicle, press shift key, and plotted path will ignore people and specific structures on its way.
Shift still doubles up as "show plotted path" in real-time, so you'll know exact course of destruction.
And if some unlucky chap happens to be on the route, this will happen:Putting "car" back in "carnage".

Amount of damage dealt to victim depends on vehicle speed and victim stance (will he be hit and fly, or just ran over).

Crepitus and robot(s) are roadkill-proof because they lack animation of collapsing... ehrm, because they are too large and would stop a vehicle, of course. So vehicles will go around them.

Same as with people, with shift pressed structures on the route will get destroyed, leaving some garbage behind, but vehicle will get slightly damaged too.

You can control which structures can be driven through and which cannot by setting Tactical Gameplay Settings > CARS_RAMMING_MAX_STRUCTURE_ARMOUR and Tactical Gameplay Settings > TANKS_RAMMING_MAX_STRUCTURE_ARMOUR.

For example default value I set for cars is 30 - you can ram through furniture, small random junk and even wooden huts in Chitzena, but you'll be stopped by trees, sandbags, rocks and brick walls.Putting "ram" back in "rampage".

For tanks I set 70 - reinforced concrete, heavy metal and rocks are safe, everything else can and will be destroyed.
Set any value to 0 to disable it completely.

Amount of damage cars take when ramming structure also depends on material armour (harder the obstacle, more damage it causes, though up to 10 armour damage is nil). Tanks don't take damage from breaking stuff.

Enemy tanks by default are in ramming mode, but will try to avoid driving over their own troops. On the other hand, they won't specifically target your mercs - any tank will still prefer to blow you up, but if you happen to be on its route, you're screwed (or maybe rather flattened).

- new feature: ramming people - set with Tactical Gameplay Settings > ALLOW_CARS_DRIVING_OVER_PEOPLE and Tactical Gameplay Settings > ALLOW_TANKS_DRIVING_OVER_PEOPLE - when shift is pressed planned vehicle route will go through people. Those who will stay on its path will be hit, causing wounds and knock-outs.
- new feature: ramming structures - when shift is pressed planned vehicle route will go through obstacles. When vehicle hits the structure on its path it will be destroyed, causing small damage to vehicle too (with exception of tank). Tactical Gameplay Settings > CARS_RAMMING_MAX_STRUCTURE_ARMOUR and Tactical Gameplay Settings > TANKS_RAMMING_MAX_STRUCTURE_ARMOUR settings control how well armoured structure can be driven through and amount of potential damage for vehicle.